The explosion on the Deepwater Horizon rig claimed eleven lives and was caused by a wellhead blowout on the sea floor that subsequently poured the full flow of the blown well into the ocean for 87 day...The explosion on the Deepwater Horizon rig claimed eleven lives and was caused by a wellhead blowout on the sea floor that subsequently poured the full flow of the blown well into the ocean for 87 days until it was finally capped on July 15th, 2010. Today the Gulf is still not oil free, and NOAA is in the process of tracking oil from the spill and assessing damages to natural resources in the region.